The parents of Michael Brown, the 18-year-old who was shot and killed by a Ferguson police officer in August, are suing the city of Ferguson.

The wrongful-death suit was filed Thursday in St. Louis County Circuit Court by Brown's parents, Lesley McSpadden and Michael Brown Sr.

The suit names as defendants the city of Ferguson, former Police Chief Thomas Jackson and former police officer Darren Wilson.

The family and its lawyers announced the suit at a Thursday morning news conference in Clayton. The parents stood by but, as in other news conferences called by the family's lawyers, neither parent spoke.

Brown, who was black, was shot and killed on Aug. 9 by Darren Wilson, a white officer. His shooting sparked protests around the country. A St. Louis County grand jury in November decided against charging Wilson, who has since resigned from the police department. The chief has also resigned.

In part, the suit contends that Ferguson police officers have a "pattern and practice of using unreasonable and excessive force" against black people. They "often escalate encounters" with blacks when the officers perceive a black person is disobeying orders, the suit contends.

"The linguistic choices uttered by Defendant Wilson indicate that he perceived (Michael Brown) to be subhuman or animal-­like, or, at times, to possess nonsensical and stereotypic superhuman powers," the suit says. For instance, Wilson said Brown looked like a demon or the Incredible Hulk and made a grunting noise during the encounter.

Anthony Gray, an attorney for Brown's family, mentioned that Hulk quote when he talked to reporters during the family's press conference Thursday. He said those kind of statements Wilson made to his supervisor should have been enough to indict him of a crime. Gray said the evidence hasn't changed, but the presentation will be different than how the county prosecutor's office presented evidence to grand jurors who considered the case and ultimately refused to indict Wilson.

Gray said Wilson's description of events has changed over time.

"He's up to his fifth version," Gray said. "It's been refined and perfected."

The suit does not seek a specific dollar amount. It seeks punitive damages and compensatory damages, including medical treatment for psychological damages. The suit also wants the circuit court to order the police in Ferguson to stop using patrol techniques that the suit says demean black residents.

The suit also asks the court to appoint a compliance monitor over use-of-force practices in Ferguson for five years or until the city can effectively train its officer on the use of force.

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